1. Field of the Invention
The present invention relates to a magnetic element switch and, in particular, to a magnetic element switch of a multi-point structure using a magnetic element, which is mounted into an electric equipment system of an automobile or the like.
2. Background
Conventionally, for a switch which is mounted into an electric equipment system to flow or interrupt a current, there has been often used a contact type structure. However, in such a contact type switch, there are drawbacks such as poor contact due to worn contact portions or contaminated surfaces, occurrences of troubles due to broken contact portions, and the like. This is the reason why a non-contact type switch is employed.
As a typical example of such non-contact switch, there is known a non-contact switch using a magnetic element which is disclosed in Japanese Patent Publication No. 58-80229. Describing the structure of this non-contact switch with reference to FIG. 25, there is provided a key top 101 which can be rotated about a rotary shaft 102 clockwise or counterclockwise, and also which includes a leg portion 104 hanging down from the key top 101, while a magnet 105 is disposed in the leading end of the leg portion 104. As the switch is operated by an operator, the magnet 105 is oscillated right and left in FIG. 25.
When the magnet 105 is oscillated left, a line of magnetic force enters a magnetic element 106 which is fixedly provided on the left side, thereby producing an electromotive voltage in the magnetic element 106. On the other hand, no line of magnetic force enters magnetic element 107 which is fixedly provided on the right and, therefore, no electromotive voltage is produced in the magnetic element 107.
Contrary to the above, when the magnet 105 is oscillated right, then the line of magnetic force enters the right magnetic element 107 to thereby produce an electromotive voltage in the magnetic element 107, whereas no line of magnetic force enters the left magnetic element 106 and thus no electromotive voltage is produced in the magnetic element 106. Further, when the key top 101 is situated at a neutral position, then the magnet 105 is also situated at a neutral position, so that no line of magnetic force enters the two magnetic elements 106 and 107 and thus no voltage is produced in the two magnetic elements 106 and 107.
As a result of the voltages produced from the two magnetic elements 106 and 107, the pressing condition of the key top 101 can be specified to perform a switching operation corresponding to the specified pressing condition of the key top 101.
Also, in the magnetic element, after a current is allowed to flow in a semiconductor to thereby produce an electric field E as shown in FIG. 26, if a magnetic flux B enters at right angles to the electric field E, then an electromotive voltage Vg is produced in a direction perpendicular to the electric field E and magnetic flux B. Therefore, if the direction of the magnetic flux B is reversed, then the direction of the electromotive voltage Vg is also reversed. Also, if the electric field E is parallel to the magnetic flux B, then the electromotive voltage V cannot be produced.
As described above, the conventional non-contact type switch using the magnetic elements is able to avoid the drawbacks found in the conventional contact type switch. However, in the conventional non-contact type switch, one magnetic element is provided for each point (the number of contacts). Therefore, especially in the conventional multi-point switch, the number of parts such as amplifiers for amplifying the outputs of the respective magnetic elements, from the number of magnetic elements down, increase, which results in increased cost. Further, because the circuit of the switch cannot be simplified, the reliability of the switch is not adequate.